Ceiling grid systems comprised of horizontal runners, for supporting tile panels such as acoustical ceiling tile are used extensively in both new and remodeled building and room structures. The grid typically consists of main runners and cross-tees, having lateral supporting shoulders or flanges, and are arranged perpendicular to each other to form a rectangular pattern. The runners most typically are suspended by a wire connected to an existing ceiling or exposed framing member, and the cross-tees are attached or mounted to the runners in a perpendicular direction to form a rectangular pattern. Less frequently, the grid is installed without suspension by nailing the runners directly to the ceiling or framing members, and then connecting the cross-tees normal to the runners. After the grid is installed, the tile panels are eased into place onto the supporting flanges of the runners and cross-tees. A grid system offers many advantages such as increasing a room's energy efficiency, improving a room's acoustics, and enhancing the aesthetic value of a room, and a suspended system is further advantageous in that it provides means for lowering a ceiling, and/or allowing for the installation of electrical fixtures, pipes and duct work.
Ceiling grid systems are relatively inexpensive and easy to install as compared to a plaster ceiling. As a consequence, there is a continuing need to improve on the design and integrity of the grid system, particularly in light of the fact that many systems are installed in commercial buildings requiring years of service, or installed by the do-it-yourself home owner. What is available or disclosed in the prior art exhibit certain deficiencies or disadvantages, however, particularly with respect to a surface mounted system. For example, U.S. Pat. No. 3,263,388 to Bogert discloses a ceiling tile installation which includes an anchor 14 having a base flange 14a for nailing to a wood joist, and a bifurcated web 14b with internal teeth 18 extending transversely from the flange. The shaped runner 15 has a transverse web 15b with teeth 18 on the outer surface which interlock with the teeth of the bifurcated web when the runner is engaged with the anchor, and the base flange 15a supports the tile panel along its marginal edge.
There is disclosed in U.S. Pat. No. 3,857,216 to Sherman a panel suspension system comprising a top element 14a of a T configuration having a web 20 with outwardly disposed teeth 30, and a bottom element 14b of a T configuration but with a bifurcated web 32 having internal teeth 33 and adapted to receive, and frictionally retain, the web of top element 14a. In practice, the top element is fastened to a joist 25, a ceiling panel 15 is then placed against the top element, and the bottom element is pushed upwardly so that the teeth of the top and bottom webs matingly engage and hold the ceiling panel in place.
U.S. Pat. No. 4,067,155 to Ruff provides a sealed joint between panels. The system disclosed is for joining and adhering a pair of abutting panels to a rigid substrate to provide a seal against thermal and moisture transfer. The system includes mating T members comprising receptacle 16 having a base 20 for nailing to a substrate, and insert 18 having a resilient, deformable cap 60. When the members are engaged and frictionally retained by reason of the mating teeth 32 and 64, a force on the resilient, deformable cap provides an upward force against the interlocking teeth thereby providing a secure engagement not susceptible to removal or loosening.
A weather tight seal for a roof or wall is disclosed in U.S. Pat. No. 3,339,329. According to the teachings of this patent, the panel cover includes an inverted channel member 12, which is nailed to the roof, and has a centrally located cleft 30 with a constriction 34. A locking bar 42 having a T-like configuration and terminating with a wedge 46 is inserted through a sealing compound 36 and into the cleft where it is engaged by the constriction.
The prior art, however, exhibits certain deficiencies or disadvantages. For example, a suspended grid system is not always necessary, and is generally more time consuming and has added expense as compared to a surface mounted system. Also, known systems typically require mounting a section only of the runners, then inserting the panel, and then mounting the remainder of the runners, whereas it generally would be simpler to first install completely the grid and then insert the panels.
The prior art discloses positioning a new ceiling over an existing ceiling in U.S. Pat. No. 4,769,965 and in U.S. Pat. No. 5,611,185. In the '965 patent, a Z-shaped runner 2 is fastened to the existing ceiling and ceiling boards rest on the horizontal flanges 8. A cross-runner 18 rests on the horizontal flanges, and an indentation and groove lock the cross-runner in position. Patent No. '185, which is assigned to the same assignees of the subject application and is incorporated herein by reference, provides a surface mounted grid system comprising a plurality of spaced main runners 14 and crossed runners 16 arranged normal to each other. The main runners comprise a top member 24 having a fascia 28 with a plurality of spaced notches 38 and a downwardly depending bottom member 26 having a horizontal flange 40. The cross-runners have horizontal flanges 40 arranged in a common plane with the flanges of the main runners, which support the tile panels. The cross-runners include connecting means for insertion in the notches upon assembly of the runners.
This invention has, therefore, as its purpose to provide an improved grid system which can be surface mounted in association with a substructure or framing member, such as a joist, and is relatively easy to install.
It is another object of the invention to provide a grid system which results in little or no loss of ceiling height, and can be installed to an existing ceiling without any need for demolition of the existing ceiling.
It is another object of the invention to provide a grid system of the above character made from a plurality of interlocking and connecting elements which can be readily assembled to yield a grid of any desired dimension.
It is yet another object of the invention to provide a grid system of the above character which provides for immediate and easy adjustment in order to accommodate tile panels of different thicknesses.
This invention has as still another object to provide a grid system of generally modular construction which lends itself to complete fabrication from regularly employed materials, particularly plastics.
In yet another object of the invention to provide a grid system which, after installation, provides easy access for opening a grid at any desired location such as the need to replace a soiled or damaged tile panel.
Still another object of the invention is to provide a ceiling grid system installed by a process which is relatively simple and less time consuming than usually required for a typical suspended grid system.